One problem with present portable communication devices such as cellular telephones is that construction of the phone is such that there is RF leakage through the keyboard which is directed towards the face of the user. Present keyboards offer little or no shielding to prevent such RF leakage. If the RF shielding is insufficient, especially in smaller phones having less physical space for shielding, manufacturers will typically set the transmitter power levels lower than normal to reduce emissions in order to pass FCC standards. Accordingly, lower transmission power levels results in reduced range of the phone.
For those cellular phones which have shielding, one current shielding method includes plating or painting. Unfortunately, plating or painting creates a myriad of problems. First, cosmetic defects are created due to overplating, often visible around the perimeter of the buttons. Plating provides no shielding at the keyhole openings, and plated fronts are often rejected due to non-uniform coating. Finally, masking is usually required for plated shielding, a process which is labor-intensive and less than cost efficient.
The use of shield cans also creates problems. Shield cans which are soldered are costly to assemble, inspect, troubleshoot, and repair. The use of shield cans is a limiting factor as to the overall size of the phone. They consume an inordinate amount of precious board space because they must contact the printed circuit board (PCB). Shield cans add more weight to the phone than other shielding processes. Finally, they inhibit the air circulation within the phone which can ultimately cause damage to temperature sensitive components.